Author Topic: CB750 AHRMA Sportsman 750 Racer  (Read 171358 times)

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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: CB750 AHRMA Sportsman 750 Racer - Post-Barber carnage!!
« Reply #1050 on: October 21, 2019, 08:01:36 AM »
Just to let you know that stock diameter valve stems will break too  :o  ;)

I have a similar souvenir piston from March 1976 but the hole is a little larger. The head was also similar except on #2. This is what I expected to see when you showed those chunks.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline RAFster122s

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Re: CB750 AHRMA Sportsman 750 Racer - Post-Barber carnage!!
« Reply #1051 on: October 21, 2019, 08:34:44 AM »
That combustion chamber is salvageable??
Figured it was toast...
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Offline bwaller

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Re: CB750 AHRMA Sportsman 750 Racer - Post-Barber carnage!!
« Reply #1052 on: October 21, 2019, 04:03:30 PM »
I remember talking to an irate Kurt Liebmann after his gorgeous CR750 had dropped another valve.....for the second time in as many weekends. 5mm stems.

Jerry is right and it does happen to larger stems, but man this is a hard pill to swallow. It'll be tough for Mike to make this call, things rattled around for a while there.
« Last Edit: December 18, 2019, 12:35:26 PM by bwaller »

Offline StanLipert

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Re: CB750 AHRMA Sportsman 750 Racer - Post-Barber carnage!!
« Reply #1053 on: October 21, 2019, 07:19:27 PM »
Any signs of the valves heat seizing in a guide? I've had this happen with cast iron guides, cured with bronze guides.

R/D dual valve springs are prone to breaking from spring surge, beehive springs cures the surging.

What valve spring seat pressure? Too mush stress on the valves?

Just speculating.

Offline MRieck

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Re: CB750 AHRMA Sportsman 750 Racer - Post-Barber carnage!!
« Reply #1054 on: October 24, 2019, 05:26:42 AM »
Any signs of the valves heat seizing in a guide? I've had this happen with cast iron guides, cured with bronze guides.

R/D dual valve springs are prone to breaking from spring surge, beehive springs cures the surging.

What valve spring seat pressure? Too mush stress on the valves?

Just speculating.
Bronze guides used with the 5mm conversion kit. Dual springs used from conversion kit. Correct IH and seat pressure. Never had much luck with RD springs.
 I have seen the 5mm conversion kits used in TQ where the engines are routinely pinned and they have survived. I don't know if it was valve material failure, spring pressure loss or what....the head is on the way back to me.
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Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1055 on: December 03, 2019, 07:53:52 AM »
Lots of things in progress right now, with the engine and chassis.

Mike has the head as well as a virgin head from me. Im thinking of starting fresh. I have discussed going with oversized intakes and stock exhaust, both with the 6.5mm stems. To offset that added weight, I will go with beehive springs, Ti retainers and adjuster nuts, and do some lightening of the rockers themselves. I won't be revving to the moon so a little added valvetrain weight won't really compromise the package, but should add some reliability to the mix.

Everything below the head went off to Kenny at Cycle X. He line lapped the main bearing bore, replaced the #4 sleeve and decked the cylinder. I also have a crank with 4 new rods and 4 new pistons coming back. This break basically kicked off a full engine refresh. Upon more inspection of the cases, it seems that the machined surface on the upper case has worn to a limit that allows the crank more lateral play than it should. You can actually see aluminum smeared on the case from crank contact. I have a ton of hours into my cases so I am looking into getting them laser welded and then machined back to size.

Beyond the engine, I have begun going end to end and finishing all the little details that have been left. Simple things like changing the arrangement of the wheel spacers in the rear to allow me to take the caliper off as a whole unit, instead of removing it from the bracket first. It's amazing what you learn after you create something about how to do it more efficiently.

I also suffered another cracked crimp collar on my oil lines. I am using Russell lines, crimps and fittings so it stands to reason they should work fine together. Well the aluminum crimp collars appear to be getting brittle once crimped and are cracking. To fix that once and for all I source stainless steel crimps from the place that does my lines and will rebuild all 3 lines with new crimps and be done with it.

The oil tank needed some love as well in the form of some new welded -6AN fittings for the breather return and a drain plug. The drain is cool as hell, with a check valve that only opens when you insert the drain fitting. It also has a nice aluminum cap to keep crud out of there.

I have a new front brake rotor coming from Australia as the last one developed cracks between some of the holes that I had enlarged to reduce weight. I also noticed that the holes in the first one did not cover the entire swept area of the rotor so there was some grooving rather than even wear going on. I will fix that with a different drill pattern that will cover the whole swept area. It will also go onto a new one-piece carrier, rather than the flat carrier with spacers I was using before. At this point, its all about refining what is there as I am overall very happy with the package.

Roebling Road in late February is fast approaching so I need to keep pressure on everything. Fortunately I have some good time off coming up for the holidays.

2020 race season, here I come!

79 days...
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1056 on: January 14, 2020, 07:30:55 AM »
More progress, with some pics this time!

Roebling is fast approaching and I have a ton of small things still in progress. The majority of the engine parts are at my place, save for some primary/cam chains and a cam chain tensioner. I also realized that I am out of middle shift forks for the trans, and need to source one before buttoning everything up. The trans is an all new pro-cut set from Kenny at Cycle X, so fingers crossed that with my more gentle use of the transmission through becoming a better racer, I won't have issues like I did before. The cases had the main bearings lapped, and will be fitted with new shells for the crank, along with new shells for the rods as well. More or less, the entire bottom end will be new or have been serviced and checked out since the boo-boo at Barber in October.

I started installing the primary chain tensioner system from Mirko as well. I am not sure if I am the only one racing with it or not, but certainly among the first few. The machining needed was simple enough, with my mill JUST big enough to handle the job. The upper tensioner needed minor trimming to fit into the upper case as the foot was touching one of the bosses for the cylinder stud, but was easily fixed. Taking the belt and suspenders approach, I safety wired the bolts as well as using some loctite, along with a light smear of Hondabond where it sits against the case.



The lower tensioner went in, again with slight trimming as the metal foot that has the bolt hole and pin was wide enough to touch a part of the casting in the lower case half, but went in quite easily.

New oil lines with stainless crimps are all done with new hoses. I should have done this item a long time ago, after splitting an aluminum collar 2 different times. The last one I noticed right before Barber as I was sitting in a chair just staring into the distance. The collar pulled off with my fingers so with 80psi of oil pressure, it could have been very bad. The stainless collars are far stronger, so that should be a done deal.



I also had a cracked front brake rotor after Barber. There were 6 or so cracks between the holes and it was time for a replacement. The cracked on was an RPE cast iron that had been drilled by them. I found that the cross drill pattern was lacking because the holes did not cover the entire swept area of the brake pad, leading to some pretty noticeable peaks and valleys in the rotor. My solution is interesting to say the least. I sourced another RPE rotor through George Schuld (thanks George!) as he was ordering some as well. I chose the non-drilled variety and after doing some reading online about the reasons rotors are drilled and decided to dimple the rotor instead. The dimple pattern covers the entire swept area of the brake pad and with smooth bottoms (round end mill) there wont be any places for cracks to propagate from. Its a bit of an experiment, but the vast majority of things I found online stated that drilled rotors today are more for looks than performance and that dimpled and slotted rotors perform to the same degree, without risk of crack formation. I likely wouldnt have had issues if I had 2 discs up front, but the stress that is put into that single rotor on a 360lb bike with a 220lb rider likely overdid it a bit. Time will tell. The rotor is out getting clear zinc plated now so it doesnt look so awful after a damp night in the paddock.



An observation from staring at this engine in pieces was that the main bearing bosses that hold the bolts (or in my case, studs and nuts) were really not flat at all, and in some cases had noticeable concavity to them. The simple solution was to index off of each hole and touch off with an end mill to get a nice flat, true surface for the nuts to rest on. In most cases, I only took about 0.007" or so off each boss to get a nice flat surface.



The last little thing is one that I have been thinking about all season, which serves no real practical purpose, but is really cool and will make people who know cb750's do a double take. I have no need for the tach drive on the valve cover any longer, so decided to get rid of it. I cut the left side out of one valve cover and grafted into the right of the one I am using. After some careful laser welding and nice fitment, I will even be able to keep the OHC logo and most of the small fins in the cover. When done, it will look like it was never there to begin with.





That's all for now, but plenty more to do as I get closer.

36 days...

All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline 754

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1057 on: January 14, 2020, 08:17:28 AM »
 Cam cover looks great,  you are leaving the lines and letters ?
 Sometimes we grind them off smooth, cuz we never forget it's an sohc 750..
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Offline MessnerMoto

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1058 on: January 14, 2020, 11:46:38 AM »
Matt post some more pictures of installed tensioner or send pictures to me

...perfection as always in your work ;)

Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1059 on: January 14, 2020, 12:04:26 PM »
Cam cover looks great,  you are leaving the lines and letters ?
 Sometimes we grind them off smooth, cuz we never forget it's an sohc 750..

Frank, the innermost line will likely need to be removed but I may try to save it. I'll remove the line from the other side as well, but the OHC will still be there. I did one like this but smooth, this cam tower hold downs a couple years ago, still needs finishing but the same idea.

Matt post some more pictures of installed tensioner or send pictures to me

...perfection as always in your work ;)

Will do Mirko!
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline MRieck

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1060 on: January 14, 2020, 12:14:46 PM »
Cam cover looks great,  you are leaving the lines and letters ?
 Sometimes we grind them off smooth, cuz we never forget it's an sohc 750..

Frank, the innermost line will likely need to be removed but I may try to save it. I'll remove the line from the other side as well, but the OHC will still be there. I did one like this but smooth, this cam tower hold downs a couple years ago, still needs finishing but the same idea.

Matt post some more pictures of installed tensioner or send pictures to me

...perfection as always in your work ;)

Will do Mirko!
Matt.....went to assemble your over the weekend and found i was out of OEM guide seals. i have others but the OEM are the best. They will be here shortly. Check this video out...go to about 29 minutes to get real good info. 
Owner of the "Million Dollar CB"

Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1061 on: January 14, 2020, 12:21:01 PM »
Cam cover looks great,  you are leaving the lines and letters ?
 Sometimes we grind them off smooth, cuz we never forget it's an sohc 750..

Frank, the innermost line will likely need to be removed but I may try to save it. I'll remove the line from the other side as well, but the OHC will still be there. I did one like this but smooth, this cam tower hold downs a couple years ago, still needs finishing but the same idea.

Matt post some more pictures of installed tensioner or send pictures to me

...perfection as always in your work ;)

Will do Mirko!
Matt.....went to assemble your over the weekend and found i was out of OEM guide seals. i have others but the OEM are the best. They will be here shortly. Check this video out...go to about 29 minutes to get real good info. 

Mike, I see just a black box and when I click it, I get nothing.
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline MRieck

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1062 on: January 14, 2020, 12:45:58 PM »
Owner of the "Million Dollar CB"

Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1063 on: January 14, 2020, 01:04:32 PM »

Very interesting. Makes me even more confident in the beehive spring being the better choice over the traditional double spring. When those fancy conical springs come the SOHC way, I may have to give them a try!!
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline MRieck

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1064 on: January 14, 2020, 03:45:32 PM »

Very interesting. Makes me even more confident in the beehive spring being the better choice over the traditional double spring. When those fancy conical springs come the SOHC way, I may have to give them a try!!
Exactly Matt.
Owner of the "Million Dollar CB"

Offline Old Scrambler

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1065 on: January 14, 2020, 06:59:10 PM »
Thanks for posting, Mike ;)............ I've been using the Ferrea version of conical springs along with their very small (light) Ti-retainers in my Salt-Flats motor with pleasing results. The answer for full-contribution to overall spring performance seems to be maximum cam-lift. 
Dennis in Wisconsin
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CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
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Offline Tracksnblades1

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1066 on: January 14, 2020, 09:35:39 PM »
Feel your pain silk....😩

Did that drop at 10k...😳?
Was that a Serdi or a dead pilot..?

Thanks for the peek inside your cases..
Are those picture windows precision milled or precision die grinder cut..?

Hope you get'r sorted...


« Last Edit: January 14, 2020, 09:40:27 PM by Tracksnblades1 »
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Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1067 on: January 15, 2020, 06:44:02 AM »
Feel your pain silk....😩

Did that drop at 10k...😳?
Was that a Serdi or a dead pilot..?

Thanks for the peek inside your cases..
Are those picture windows precision milled or precision die grinder cut..?

Hope you get'r sorted...

It went at about 8k rounding T2 at Barber, with me in 2nd place, 3 laps to go. Would have been nice to cap the season off with one more podium and not grenade the motor, since it was coming down for a look over at the end of that race, but I guess I learned my very valuable, and expensive, lesson.

I believe Mike does Serdi valve jobs.

The windows were hand cut with drills and a right angle head for my Dremel tool. Im not sure how much support the small bridge between sleeve holes in the upper case actually provides, but in the future, I may just put the top half in the mill and cut down through to make the windows for any future builds.
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline Ramrod_Racing

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1068 on: January 15, 2020, 09:45:30 AM »
Great to see your progress. No lie, Roebling is coming up FAST.

Offline Tracksnblades1

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1069 on: January 15, 2020, 03:57:37 PM »
Silk,
Does your plans for next round include: CRF type pistons...?
                                                          Oil jet piston cooling?

Those bridges above your magic windows  disappear when boring for
JMR big block....and newer engines don't seem to utilize them any more....

What lift was your exhaust valve seeing?
Was you running a 410 cylinder head?

I like your magic windows and your pan-a-vac system......
Age Quod Agis

Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1070 on: January 15, 2020, 05:32:08 PM »
Silk,
Does your plans for next round include: CRF type pistons...?
                                                          Oil jet piston cooling?

Those bridges above your magic windows  disappear when boring for
JMR big block....and newer engines don't seem to utilize them any more....

What lift was your exhaust valve seeing?
Was you running a 410 cylinder head?

I like your magic windows and your pan-a-vac system......

What are CRF pistons? Im already running 62mm 12:1 pistons that Kenny and I worked on, incorporating many of the best modern piston features.

I thought about some additional way to cool the piston but have not explored it further.

Good to know about the magic windows and the small bridge between holes in the upper case.

I was running three CX7 cam and will again this year on a 392 head. I do have a 410 head that I may use on my bigger bore superbike racer project though.

The venting system on the engine seems to work nicely. It can never fill up and the only oil issues I had were related to gaskets on side covers so I'd say it's doing its job.
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline Tracksnblades1

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1071 on: January 15, 2020, 06:43:01 PM »
Silk,

Honda CRF/CBR pistons...The one below is 2 ring wiseco...

2012 Kawasaki Ninja 250R has 62mm standard 3 ring piston.i
(It will have a narrower wrist pin rod witdth than the stock .900 sohc little rod end width.)
With a compression height that would allow for higher rod/stroke ratio.
The 2 ring version would allow even more rod...Without any spacers...😎

« Last Edit: January 15, 2020, 07:37:29 PM by Tracksnblades1 »
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Offline PeWe

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1072 on: February 16, 2020, 03:01:03 AM »
Sorry to remind you about the failure....
Did you find the root cause of the valve failure?
Cam caps/holder threads all OK?

I saw a similar head here last year. Also a 750 classic racer using 5mm stems (34/28mm), K head. Ex valve dish sat like a crashed UFO into the piston crown. JE pistons shaped after the chambers. I should have taken a photo since it looked very special with dish only vertically into piston crown

In that case a loose cam cap/holder that probably caused a huge valve lash,  lash cap flew off, engine sounded bad but not stopped direct, stem could have been bent and snapped off when rocker arm/adjuster screw aimed wrong....
That was only one valve. Head could be fixed by welding chamber, installing a new seat and final machining. A Carillo rod wasted and crank too if I remember correctly.

I use Kibblewhite 5mm stem valves 34/28 on my 1005cc street bike so the first dropped valve here got me to think, now this.
- I guess that an adjuster screw that loose the nut can end up in lost lash cap that make it possible to cause side forces to the valve, finally snapping it off.

The 5mm valve stem look really thin without lash cap that make the landing area for adjuster screw much wider.
The installed 5mm stem valves with springs feels rather flimsy when bending them a little by hand compared with stiffer 6.5mm stem and old style race springs.

I have had thoughts to replace the valve cover using one I have with bolts keeping cam holders down as an extra insurance. My cam caps/holder threads have all glued time-serts and all M6 bolts carefully tightened, not too much.

But you never know, one nut coming loose might be enough for for a really bad domino effect draining the wallet, money that could have been used for two, travel to a sunny warm place with cooling drinks.  8)

I'm sure you will have an even better engine for 2020! ;)
« Last Edit: February 16, 2020, 12:23:18 PM by PeWe »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline bwaller

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Re: CB750 AHRMA Sportsman 750 Racer
« Reply #1073 on: February 16, 2020, 06:36:45 AM »

I'm sure you will have an even better engine for 2020! ;)

+1 PeWe.  Just a few days to go Matt, I hope it's coming together well.

Offline slikwilli420

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Re: CB750 AHRMA Sportsman 750 Racer - Roebling report
« Reply #1074 on: February 25, 2020, 12:47:03 PM »
Well dudes and dudettes, Im back from round one of my 2020 season and it was a great one.

The bike came to life Sunday the 16th for the first time after a full motor build and ran like a champ. The bike has a bit of a new look this year with a new seat as well as some smaller details like plated/dimpled front brake rotor and modified breathing system for the oil tank, but it mostly unchanged. The new head has 6.5mm stems, oversized intakes and was ported by Mike Rieck to perform best with my current carbs (per the rules). Four new rods, four new pistons and a new trans later, and its like nothing ever happened!!

The Mrs. couldnt make the trip this time, so for the first time in my racing life, I was heading out solo. The 14hr drive was made more manageable by doing some on Wednesday and finishing up Thursday. I arrived at the track Thursday afternoon to rain and 40 degree temps, neither is conducive to unloading gear and setting up camp. Fortunately for me, my wife booked hotel accommodations for the entire trip, so I was able to enjoy warm, cozy sleep under a real roof all weekend.

Friday morning came nice and early and I was at the track by 7:30AM. The bike went through tech flawlessly (as always) and it was time for 4 rounds of practice.

I've been here once before but I always take the first practice to brush the rust off from not racing for a while and get to know the track again, and it was like 35 degrees outside at that time. Neither I or the bike had operated on a track in temps that cold, so I had no clue how the tires would warm up and when I would get good grip. Naturally, lap times we abysmal due to all of that.

After parking the bike in the pits, I noticed a bit of oil coming from under the stator plate/shift cover area. I went round and round fighting a few small oil leaks all day, eventually using thread sealant on each of the main stud nuts, as well as on the oil pan drain plug. My drain plug is from Joker Machine and has an aluminum "crush" washer. Problem is that the aluminum its made from is so hard, it doesnt really crush. Id had issues with this in the past and never took the time to remedy the issue with a proper soft copper crush washer, which WILL be done before next race. The nuts on the mains leaking is another thing that is really annoying to me. I get the benefit of the studs but the ability for oil to make its way between the case halves, down that stud and out the bottom of the motor is maddening. I was able to find some grade 10.9 acorn nuts from McMaster that I am going to try to replace the nuts. It seems that the tip of the stud is the biggest offender, as if oil is getting past the threads rather than out from under the nut flange. I thing with some copper crush washers as used on many other head nuts with higher torque, the 17.5ft lb these are torqued to should be no issue at all.

Friday after practice as the sun sets on a beautiful, cold day of practice:


Saturday, race day. I skip practice #1 for the day since it was still about 35 degrees out and riding around at 75% of pace is useless to me so I waited until the next round and went out. Lap times are still not stellar, and I think its mostly to trusting that the tires are warm enough to do the job. Coming off the track and checking pressures tells me they are heating up nicely as intended. I was race 13 on the schedule, last of the day. It sucks being last especially on Sunday as people peel out when they are done racing so it starts getting pretty sparse in the pits for a race that late. The benefit to being last was it was still the hottest (hottest being 58 on Saturday and about 65 on Sunday) part of the day so I had more confidence in tires coming up to temp quick for a strong race.

The hot bikes in my class this weekend were both Triumph twins, punched to 750, both with fast riders, one of which is who beat me pretty good last year on Saturday. The other guy was a front runner at Barber last year, so I knew there was work to do on my part to make a good race. I lined up with the guy from last year, and the other guy on the row behind. I had, without question the best start of my whole racing life. The front tire carried a few inches above the ground until torque fell off and the wheel touched down, just in time for 2nd gear. I see the guy from the second row pass me, but he was the only one. I was sure the other guys was hunting me all race, as I tried to catch the other fast Triumph. He pulled away without a ton of effort on his part and while I tried to keep up with him, he steadily pulled away. I knew then that I wasn't hunting 1st, but defending 2nd! I rode hard all 8 laps of the race, trying to keep steady and not beat myself to death before the finish, just knowing that the other rider was hunting, waiting for me to screw up and take advantage. The white flag came with me in 2nd and I said to myself as I always do "Don't f*ck this up, 1 more lap and you're locked in 2nd!" and so I rode that lap as strong as I could and never saw him even once, crossing the finish line in 2nd place.

I pulled into the pits and stripped off my gear to get ready for the awards ceremony and meet the guy that won. He reaches out to shake my hand and congratulate me on winning. Clearly I have no clue in hell what he's talking about and he explains that on lap 3 (far enough out of my sight that I didn't see him) he had a bad spark plug boot that came off and wouldn't go back on, forcing him off the track. I had won! No matter that it was by default, as my uncle always says "To finish first, first you must finish!" I was pretty thrilled to start the season off that way and was looking forward to another run at him tomorrow, now that his bike had fresh plug boots on both wires.

Getting that top box plaque:




Sunday's racing starts with one round of practice, which again, was colder than a witches titty, so I skipped in favor of warming up the bike with some scrub laps ahead of my race. Grids are redone to reflect points accumulated from Saturdays racing, so now I was lined up on one row with the two fast Triumphs, ready to drag race to turn 1. The green flag drops and I get a pretty good start again, but not as amazing as the day before, and of course the one Triumph pulls out ahead as I drag race the other into turn 1. I follow the fast guy (same guy from Saturday with the bad plug wire cap) and start pushing to close the gap he opened up. Again, after about 1 lap he had enough space in front of me and I was riding at my comfort limit, I settled in to stay in 2nd and not screw anything up. The Thruxton class started behind us again and a few of those guys made their way around me. Each time I heard a Triumph engine, I knew it was the other guy, back for redemption from yesterday, but each time it was a rider in the other class. I approached lapped traffic about half way through the race and used them as a chance to work on passing other riders as well as to create a buffer between me and the guy behind me. The last few laps were quiet for me, just keeping my head down and putting in the best laps I could, and this time, finishing in 2nd place for real.

After reviewing lap times from both days, it turns out that not only was my fast lap on Sunday 2.3 seconds faster than Saturday and 5.5 seconds faster than last year, all my Sunday lap times beat my best on Saturday! That means that Sunday was far faster and more consistent than any other time I had been on that track. The thing is that I know there is so much more in that bike, I just need to get it out of me.

A few action shots from the weekend:








Next up is racing in Kershaw, SC at Carolina Motorsports Park.

Leaving in 29 days...

All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html